2314 高強度鋼の二段変動荷重下における超長寿命疲労特性と内部き裂進展挙動(S07-3 疲労強度,S07 構造材料の疲労強度とき裂進展問題)  [in Japanese] 2314 Ultra High-Cycle Fatigue Characteristics and Interior Crack Growth Behavior under Repeated Two-Step Loading on High Strength Steel  [in Japanese]

This paper presents the fatigue behavior of high strength steel, SCM435, under constant amplitude loading and repeated two step loading in ultra high-cycle region. The axial loading fatigue tests of R=-1 was conducted at frequency of 1〜200Hz. The area that was called the Fish-eye and FGA was observed in the fracture surface. In addition, beach marks were observed in Fish-eye under repeated two-step loadings. However, signs of the Two-step loading like the beach mark were not observed in FGA. In addition, it was forecast that a low stress and a high stress did not mutually influence the growth of FGA since it became a value close to one by using the Minor low.